OTTAWA - Ottawa police are still on the hunt for a teenage girl who allegedly lured other young girls over the Internet and then forced them into prostitution in what investigators call a stunning cautionary tale about the perils of social media.

Two 15-year-old girls are already in custody, charged with luring girls — one as young as 13 — through social networking sites, then turning them over for prostitution with adult males.

One of the accused was in court Tuesday, the other is due in court on Wednesday. The third suspect, 17, is still at large.

"It's terrible," said Staff Sgt. John McGetrick, who called an impromptu news conference Tuesday to better deal with the crush of media attention the case is getting.

"Our folks deal with disturbing investigations every day, but this one is shocking."

Police allege that on three separate occasions, the three accused used social media to contact three female victims ranging from 13 to 17 years of age. After meeting at a residence, they then took the girls to other locations for the purpose of prostitution.

He said the victims and suspects met online, but may have "distantly" known one another.

McGetrick made a point of telling parents to pay close attention to what their kids are doing on Facebook, Twitter and other popular social media services.

"Know who your kids are talking to online," he said.

"If they are going to meet someone you're not familiar with, ask them: 'How did you meet them? Did you meet them online? What did they say?'

"If I'm a parent, I'm going to have access to my kids' accounts and I'm going to read them. If they don't like it, that's unfortunate."